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- Dynatron vacuum tube signal generator, 1931. It covered the range 1.8 to 15 MHz. The circuit was used in signal generators due to its frequency stability, which was compared to crystal oscillators (en)
- An early tetrode, the RCA 24-A from 1929, showing on the lefthand side the negative resistance "kink" in the curves due to secondary emission. At a screen voltage VC2 of 90 V it has negative resistance between about Vp = 10 to 60 V. (en)
- The dynatron oscillator circuit was also used as the local oscillator in early vacuum tube superheterodyne radio receivers, such as this 1931 Crosley model 122 seven tube radio. (en)
- A modern tetrode, the 6P25. Due to a coating on the plate, there is very little secondary emission, so there is virtually no negative resistance region in the curves, making this tube unusable for dynatron operation. (en)
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